This is not really verifiable as no one can verify (in an absolute sense) that you don’t secretly know the private key to the public key that leads to the, e.g., all-zero hash. It’s just extremely unlikely that you do, and would contradict the security of the hash function. Choosing values like that is a common method used in cryptography standards, sometime referred to as “nothing up my sleeve” numbers/values. The output value of the hash function has to be plausibly independent of the hash function itself, so you could use the all-zero string or some bit sequence obtained from pi or e or something like that.
Currently, neuron information such as the controller and the following graph are generally only queryable for the controller or hotkeys associated with a neuron. This will change soon with the advent of public neurons.